Semiconductor devices are used in a variety of electronic applications, such as personal computers, cell phones, digital cameras, and other electronic equipment, as examples. Semiconductor devices are typically fabricated by sequentially depositing insulating (or dielectric) layers, conductive layers, and semiconductive layers of material over a semiconductor substrate, and patterning the various layers using lithography to form circuit components and elements thereon.
A transistor is an element that is utilized extensively in semiconductor devices. There may be millions of transistors on a single integrated circuit (IC), for example. A common type of transistor used in semiconductor device fabrication is a metal oxide semiconductor field effect transistor (MOSFET), as an example. Transistors of semiconductor devices are typically formed by depositing a gate dielectric material over a substrate, and depositing a gate material over the gate dielectric material. The gate material and the gate dielectric material are patterned using lithography techniques, and dopants are implanted into the substrate proximate the gate and gate dielectric to form source and drain regions.
Sidewall spacers are typically formed on the sidewalls of the gate and gate dielectric, either before, after, or both before and after the dopants are implanted into the substrate. Sidewall spacers typically comprise silicon nitride, and are usually formed by depositing a layer of silicon nitride over the gate, gate dielectric, and exposed portions of the substrate, and etching the layer of silicon nitride to remove the layer of silicon nitride from the top surface of the gate, and from over the top surface of the substrate, yet leaving the silicon nitride disposed on the sidewalls of the gate and gate dielectric, forming a nitride spacer.
Controlling the thickness and width of nitride sidewall spacers is difficult. Forming uniform sidewall spacers across a surface of a semiconductor device is a key factor in obtaining uniform device performance in some applications.
Thus, what are needed in the art are improved methods of forming insulating spacers for features of semiconductor devices.